1. Field of the Invention
The present invention relates generally to remote, pressure operation of electric switches and, more particularly, to electromagnetically transparent fluidic operators adapted to conventional electric switches for operating the electric switches remotely and to a method of adapting electric switches for remote, fluid operation.
2. Description of the Prior Art
When testing battery operated systems to electromagnetic stimulus, such as in electromagnetic interference studies and radiated susceptibility studies, it is desirable to switch the system power "on" and "off" between test shots to conserve battery charge. It is further desirable to switch the system power "on" and "off" from a remote location to eliminate down times associated with accessing the systems directly. Attempts to modify the original power supplies for the systems to permit remote switching such as, for example, by adding at least a remotely operable switch and a remote control receiver, are usually incompatible with electromagnetic testing due to the size, configuration and cost of the modifications as well as the effect the modifications have on the electromagnetic coupling characteristics of the systems. In addition, different systems to be tested typically require different switch designs in accordance with the size, weight and power requirements of the systems. The specialized switch designs of diverse systems are often not amenable to modification for remote switching and, even where modification is possible, the modifications are often not cost-effective to undertake and/or reproduce.
Remotely operable electric switches using pressure, such as fluid pressure, radiation pressure and sound pressure, as the switching signal have been proposed for remote operation. Remote, pressure operated electric switches typically employ various mediums as control links including liquid, gas, light, electrical radiation and sound. Representative of prior art pressure operated electric switches are U.S. Pat. Nos. 5,139,357 to Rents, 4,900,883 to Brane et al, 4,855,545 to Kreuter, 4,755,638 to Geberth, 4,468,532 to Clark et al and 4,037,317 to Bauer et al as well as Models 506019, 506038 and 506039 of pressure switches manufactured by Bristol Babcock, Inc.
Conventional electric switches redesigned or modified for remote operation as well as conventional, remotely operable electric switches including those that are pressure operated are frequently not suitable for use in electromagnetic testing. Most conventional, remotely operable electric switches have a high metallic content and require expensive support hardware, such as a remote transmitter, receiver and/or communication link. Conventional electric switches having radio frequency control links are incompatible with electromagnetic testing due to possible interference of the RF switch signal and the RF test signal as are hard wired switches with metallic wires that can corrupt the electromagnetic characteristics of the associated system. Although fiber optics/light controlled switches are suitable for use in electromagnetic testing, the latter switches have the disadvantages of requiring an electronic transmitter and receiver, necessitating a specialized design depending on the power requirements of the system, and adding some amount of extraneous metal, in addition to the electric switch, to the system due to the fiber optic receiver imbedded therein. Furthermore, fiber optic transmitter circuitry within the system can be susceptible to electromagnetic test fields causing the circuitry to function improperly. Liquid pressure switches can be compatible with electromagnetic testing where the liquid is non-conductive; however, complications from leaking present an unacceptable risk. Although air-operated pressure switches are theoretically compatible with electromagnetic testing, conventional air-operated pressure switches are prohibitively large and comprise metallic components. Modifications or adaptations of conventional air operated electric switches are typically not easily applicable to different types of electric switches, for example, single pole double throw and double pole double throw electric switches. Indeed, many prior art remotely operable electric switch designs are themselves complete switches and not modifications of existing, off-the-shelf electric switches. Accordingly, the prior art has thus far been deficient in providing an electromagnetically transparent adaptation of an existing electrical switch to allow the electric switch to be operated remotely.